Conversion of short-chain alcohols to energy-dense hydrocarbon fuel mixtures | The George Washington University

Conversion of short-chain alcohols to energy-dense hydrocarbon fuel mixtures

Case ID: 022-009-Voutchkova

Researchers at the George Washington University have invented a novel mechanism and catalyst to convert a wide variety of alcohols to hydrocarbons and other by-products with high selectivity and lower energy requirements compared to other methods.

Multi-step H2-free upgrading of alcohols to liquid hydrocarbons is highly desirable for producing drop-in fuel substitutes, but the limited reports of this process for select substrates require multiple catalysts and base, resulting in limited applicability. Direct conversion processes that do not require base are yet to be reported. We have developed a mechanism and catalyst which has complete deoxygenative coupling of alcohols with heterogeneous Pd catalysts, immobilized on acid-base supports, which actively participate in the reaction cascade.

The supports include primarily basic, acidic and amphoteric clay-based supports, with a combination of Lewis acidic and basic sites. At temperatures < 200oC the optimized catalysts afford ~30% long-chain hydrocarbons and ~ 30% long-chain alcohols and esters, all of which are more energy dense than the parent alcohol. The reaction to hydrocarbons proceeds via tandem dehydrogenation, aldol condensation and decarbonylation (Scheme 2).  The product mixture can be tuned to suit fuel needs – from petroleum to jet fuel – by changing the starting alcohol and the catalyst used. Optimizing selectivity for deoxygenative coupling requires synergy between active Pd species and support basic sites, as well as optimization of the four sequential catalytic steps required for the overall transformation. Catalysts are extensively characterized and are robust under reaction conditions.

For reference, we've included Scheme 1, which are current approaches to upgrading alcohols primarily rely on the Guerbet condensation, which affords longer-chain, branched primary alcohols through sequential dehydrogenation, aldol condensation and hydrogenation reactions (Scheme 1, Reaction A). While the Guerbet reaction partially deoxygenates alcohols, the current technology results in complete alcohol deoxygenation via deoxygenative olefination, which results in higher energy density, (Scheme 1, Reaction B).

Scheme 1 - Upgrading of primary alcohols to longer chain alcohols (a) and hydrocarbons (b).

Scheme 2 - Proposed mechanism for deoxygenative olefination of alcohols to hydrocarbons and other by-products.

Applications:

  • Conversion of wide variety of alcohols into energy-dense hydrocarbon fuels

 

Advantages:

  • Can cover numerous types of alcohols into hydrocarbons
  • High reaction selectivity means getting better yields
  • Relatively low temperature needed to sustain the reaction

 

Patent Information:

Title App Type Country Patent No. File Date Issued Date Patent Status
Conversion of Alcohols and Aldehydes to Energy-dense Hydrocarbon Fuel Mixtures US Utility *United States of America   2/14/2023   Published

For Information, Contact:

Michael Harpen
Licensing Manager
George Washington University
mharpen@gwu.edu

Inventors:

Adelina Voutchkova-Kostal
Diana Ainembabazi
Darren Dolan
Jonathan Horlyck
Keywords: